With the aging of industrial plants, many plants need to be rebuilt. A primary reason for failure of an industrial plant is a breakdown of its piping system owing to stress applied to the system. Stress results from heating and cooling of fluids in the pipes which causes them to expand and contract. Stress also results from improper fitting of pipes during initial construction. Sections of pipe are connected at their ends, generally by welding. For a proper fit, the end surface of a new or replacement pipe is cut and beveled to match the end surface of an existing pipe. For large pipes, i.e. those having a diameter on the order of 20 inches or more, a cutting tool is used either to cut a section of pipe to length or to trim the end surface thereof to match the end surface of the pipe with which it is to be connected. The cutting tool, which may weigh as much as 200 pounds, is positioned on the pipe, to cut the edge to a desired configuration. Unfortunately, much guesswork is involved in positioning the tool which is also cumbersome to adjust. Using trial and error, a pipe fitter cuts the pipe to as close an approximation of the proper end surface configuration as possible. Then the pipe sections are connected together.
The present invention relates to a method and apparatus for cutting and fitting pipes so that they are properly aligned for welding to create a stress-free piping system. The invention may also be used in the replacement of worn or damaged pipe sections under stress.
Laser devices for centering pipes are well-known in the patented prior art as evidenced by the to Davis U.S. Pat. No. 6,052,911. As disclosed therein, a laser is rotatably connected with a frame which is mounted on the pipe. The axis of the laser is aligned with the centerline of the pipe and is used to provide marks which assist in aligning a new pipe parallel to an old pipe.
While the prior devices operate satisfactorily, they are rather cumbersome and do not afford the opportunity for a pipefitter to both align and cut a section of pipe with a single instrument, which greatly reduces the time and increases the accuracy of the cutting process. The present invention was developed in order to overcome these and other drawbacks of the prior devices by providing an improved method and apparatus for efficiently aligning and cutting pipes, particularly metal pipes in the piping system of an industrial plant. It will greatly enhance the ability of a person of average pipe cutting and fitting skills to install or replace pipes in the piping system.
Accordingly, it is a primary object of the present invention to provide a method and apparatus for aligning and cutting a cylindrical pipe having a longitudinal axis in which a frame or ring is mounted on the periphery of the pipe and has a laser mounted thereon. The laser generates a linear laser beam and the frame is adjusted so that the beam is directed onto a fixed remote target corresponding with the end of another pipe. Once adjusted, the frame is secured in place and a cutting tool is used to cut the pipe in a configuration to match and mate with the end of the other pipe.
According to a further object of the invention, a plurality of lasers are provided on the frame in spaced relation. The lasers are preferably adjustably connected with the frame so that the beams therefrom can be directed at selected angles relative to the longitudinal axis of the pipe.
It is yet another object of the invention to align and cut a damaged section of pipe for removal and to align and cut both ends of a replacement section of pipe for a precise fit of the replacement section with minimal stress after welding the replacement section.
A further object of the invention is to provide a method and apparatus for aligning and cutting a cylindrical pipe adjacent to an elbow portion thereof by mounting a ring on the pipe about the pipe circumference before the elbow portion and establishing a pair of first reference points spaced 90xc2x0 relative to a longitudinal axis of another pipe at a remote location beyond the elbow and establishing a pair of second reference points on the ring and spaced 90xc2x0 relative to a longitudinal axis of the pipe. The ring is adjusted to a fixed position so that the pair of second reference points are oriented in a configuration corresponding to the pair of first reference points to define a cutting location so that after cutting, the cut end surface of the pipe will be in 90xc2x0 alignment with the end of the first pipe.
According to another object of the invention, the ring is adjusted on the pipe via triangulation.